php merge array function array_merge()

array_merge() function merges arrays in php. It can combine multiple arrays into one array without changing the original array. It’s worth it, but today I encountered several small details when using array_merge to merge arrays. Let me give you an example below

1.array_merge() merge

$array = array('a'=>'bb');
$array2 = array('b'=>'cc');
$array3 = array_merge($array,$array2);

The output result is

Array ( [a] => bb [b] => cc )

There is no problem because the above are all arrays. If we set $array to not be an array, let’s see what happens.

$array = 1;//array('a'=>'bb');
$array2 = array('b'=>'cc');
$array3 = array_merge($array,$array2);
print_r( $array3 );

After running The result

Warning: array_merge() [function.array-merge]: Argument #1 is not an array in E:test1.php on (www.jb51.net)line 4

tells us that we must have an array, so I have many ways to solve this,

1. Use is_array() to judge, but you will find that if you merge the arrays More often than not, each judgment is unreasonable. Later, I found that the data class can be converted

$array = 1;//array('a'=>'bb');
$array2 = array('b'=>'cc');
$array3 = array_merge((array)$array,(array)$array2);
print_r( $array3 );
输出结果不报错了
Array ( [0] => 1 [b] => cc )

. It automatically converted the number 1 into an array, so everyone must pay attention to these when using it. Oh the details.

Merge two arrays into one array:

<?php$a1=array("a"=>"red","b"=>"green");$a2=array("c"=>"blue","b"=>"yellow");print_r(array_merge($a1,$a2));?>

Definition and usage

array_merge() function is used to merge one or more arrays into one array.

Tip: You can input one or more arrays to the function.

Note: If two or more array elements have the same key name, the last element will overwrite the other elements.

Note: If you only input an array to the array_merge() function, and the keys are integers, the function will return a new array with integer keys whose keys start with 0 starts reindexing (see Example 1 below).

Tip: The difference between this function and the array_merge_recursive() function is that it handles the case where two or more array elements have the same key name. array_merge_recursive() will not perform key name overwriting, but will recursively form multiple values ​​with the same key name into an array.

Syntax

array_merge(array1,array2,array3...)

array1 Required. Specifies an array.

array2 Optional. Specifies an array.

array3 Optional. Specifies an array.

Return the merged array.

Use only one parameter with an integer key name:

<?php$a=array(3=>"red",4=>"green");print_r(array_merge($a));?>

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